1. Field of the Invention
The present invention relates to a liquid extraction apparatus, and in particular, to an apparatus for extracting a liquid from any one of a plurality of liquid containers, whether the container has an open mouth or a stoppered mouth.
2. Description of the Prior Art
In the field of automatic analysis instruments a premium is placed on the ability of an instrument to process a relatively large number of different liquid samples without operator intervention. Liquids which are non-toxic and non-hazardous in nature are carried in open containers, such as open test tubes. However, to avoid exposing operators to contact with a potentially hazardous material, any unsafe liquid material is carried in a closed container, i.e., a container whose mouth is closed by a rubber stopper or other suitable cap mechanism. Exemplary of a suitable closed container is that container sold by Becton-Dickinson Company, East Rutherford, N.J., under the trademark Vacutainer.RTM.. Such a container is evacuated to facilitate aspiration of a whole blood sample.
Complications are encountered with the use of an evacuated closed container. One complication is the need of a relatively more substantial extraction needle to penetrate the rubber stopper. A further complication is the difficulty in extracting accurately a predetermined volume of liquid due to air pressure within the tube. This problem has been addressed by using an outer penetrating needle to puncture the stopper and equalize air pressures followed by the insertion of an inner liquid extraction needle to aspirate liquid.
In addition to being able to aspirate liquid sample from both open and stoppered containers, to effectuate versatility in handling sample containers from a variety of sources it is important that a sample probe apparatus be able to automatically identify and accomodate containers having different physical characteristics, in particular, containers that are stoppered or open-mouthed or that have different heights and diameters.
In view of the foregoing, it is believed advantageous to provide a liquid extraction apparatus having the ability to identify the type of sample container from which a liquid sample is to be extracted. Moreover, it is also believed advantageous to provide a liquid extraction apparatus having such flexibility of operation as to extract liquid samples from either stoppered or open containers using a single needle.
U.S. Pat. No. 3,991,627 (Laird et al.) discloses a device for aligning sample containers (within some predetermined range of sizes) regardless of the container's size. The device has an outer piercing needle that passes throught the septum of a container and an inner needle movable within the piercing needle. Liquid is aspirated from the container through the inner needle.
U.S. Pat. No. 4,951,512 (Mazza et al) discloses a liquid extraction apparatus employing an outer puncture tube to form a temporary opening in a stopper of a sample liquid container and an inner extraction needle to remove an amount of liquid from the container. A lift assembly moves a sample container upward against the puncture tube. After liquid is extracted a stripper assembly strips the container from the puncture tube, allowing the opening to close.
Other devices that employ an outer puncturing tube and an inner liquid extraction needle include U.S. Pat. Nos. 4,478,095 and 4,577,514 (both to Bradley et al.) and U.S. Pat. No. 4,721,137 (Mueller).
U.S. Pat. Nos. 4,756,201 and 5,201,232 (both to Uffenheimer) both disclose an apparatus that extracts liquid from open and closed containers. These apparatus both additionally require that a closed tube be segregated by an operator and positioned upside-down for extraction to occur.
U.S. Pat. No. 5,270,211 (Kelln) accomodates sample containers of different heights using an elevationally movable arm carrying a receptacle for receiving the containers. A spring-biased tube clamp urges each container against rib guides within the receptacle to transversely center containers of differing diameters. A puncture tube is used to puncture resealably a conventional closure on a container and a pipette is positioned within the puncture tube to extract sample liquid from the container. A bifurcated stripper engages the upper surface of a container to prevent upward movement of the container during removal of the puncture tube.
U.S. Pat. No. 5,080,864 (Shaw) discloses a stopper detector using a rotating flag-like mechanism for use in conjunction with a stopper remover.
U.S. Pat. No. 4,962,041 (Roginski) provides a single extracting needle that is lowered to puncture a stopper closing a liquid container and withdraw a sample liquid. A retainer having a latching mechanism prevents the withdrawal or loosening of the stopper due to friction generated during the withdrawal of the needle from the stopper.